Composite separators

Chemical Inhomogenities or Compositional Separation. Compositional separation at the grain boundaries influences the magnetic interactions of the individual grains. Deposition parameters such as temperature, substrate material, and the use of a seed layer play an important role. 

There are, in principle, two driving forces for obtaining the compositional separation, namely the temperature and deposition geometry. 

A composite separating agent has been produced by filling soft gels such as dextran and a agarose, which have poor mechanical strength but effectively... 

Every separation process divides one or more feeds into at least two products of different composition. Separation processes that operate on heterogeneous feeds usually involve screening or settling. Those that involve physically homogeneous mixtures must use more subtle means to create products of different composition. These latter processes are pervasive in industry they consume large amounts of energy and require sophisticated research and design. 

As we indicated in Chapter 13, the requirement that all phases be at the same pressure at equilibrium does not apply in all situations, and in particular, it does not apply to two phases of different composition separated by a rigid membrane. If the membrane is permeable to only one component, we can show that the pressure on the two phases must be different if equilibrium is maintained at a. fixed temperature. 

Asahi Chemical Industry carried out an exploratory investigation to determine the requirements for cellulose based separators for lithium-ion batteries. In an attempt to obtain an acceptable balance of lithium-ion conductivity, mechanical strength, and resistance to pinhole formation, they fabricated a composite separator (39—85 /cellulosic fibers (diameter 0.5—5.0 /pore diameter 10—200 nm) film. The fibers can reduce the possibility of separator meltdown under exposure to heat generated by overcharging or internal short-circuiting. The resistance of these films was equal to or lower than the conventional polyolefin-based microporous separators. The long-term cycling performance was also very comparable. 

Zirfon separator is a new alternative for Ni—H2 batteries. It is a porous composite separator material composed of a polysulfone matrix and ZrOz, which is present in a powder form. The manufacturing is based on the film-casting technique. It is very stable in concentrated KOH solutions at elevated temperatures. These films are around 300 /iin thick. SORAPEC has tested Zirfon in Ni—H2 cells and has indicated that it is one of the best separators. 

Figures 6 and 7 illustrate the preposed mechanism in OC. Using the specific example of a separation of a styrene n-butyl methacrylate copolymer, the first SEC separates the copolymer according to molecular size in solution. At any desired retention time, the flow in the first instrument is stopped and an injection made into the second instrument of a single molecular size "slice" of the chrcoiatogram. The solvent running in the second instrument is a mixture of tetrahydrofuran (THF) and n-heptane. THF is a solvent for both styrene cuid n-butyl methacrylate portions of the polymer molecules. However, n-heptane is a nonsolvent for the styrene-rich portions. As a result, vrfien the injection is made into the second instrument, the styrene-rich molecules will shrink relative to the n-butyl methacrylate-rich molecules. An immediate size distribution will be present vrfiich will reflect the composition differences. The smaller styrene-rich molecules will enter more pores of the column packing than their n-butyl methacrylate-rich counterparts and so be fractionated. Furthermore, since the styrene-rich molecules "hate" the mobile phase, they should find the surface area of the packing more "sticky" than the n-butyl methacrylate-rich molecules. Thus, again the styrene-rich molecules should be retarded relative to the others. According to this picture, the mechanisms of size exclusion, adsorption and partition are thus able to act synergistic ally to accomplish a composition separation.

The effect of dispersoids on the mechanical properties of metals has already been described in Section 5.1.2.2. In effect, these materials are composites, since the dispersoids are a second phase relative to the primary, metallic matrix. There are, however, many other types of composite materials, as outlined in Section 1.4, including laminates, random-fiber composites, and oriented fiber composites. Since the chemical nature of the matrix and reinforcement phases, as well as the way in which the two are brought together (e.g., random versus oriented), vary tremendously, we shall deal with specific types of composites separately. We will not attempt to deal with all possible matrix-reinforcement combinations, but rather focus on the most common and industrially important composites from a mechanical design point of view. 

The unusual sensitivity of some composite-modified double-phase propellants before curing has justified intensive effort to exploit a nonmechanical mixing process. First introduced in about 1959 as the quick-mix process by Rocketdyne Division of North American Aviation (5, 10), the inert diluent process has been developed at the Naval Ordnance Station, Indian Head, Md. for application to a variety of propellant compositions. Separate streams of solids, slurried in heptane, and an emulsion of plasticizers in heptane, are combined in a non-mechanical mixing chamber. The complete propellant slurry is allowed to settle, and the heptane is separated and recycled in a continuous operation. Figure 1... 

The solar system formed from a well-mixed collection of gas and dust inherited from its parent molecular cloud. The bulk composition of this material, as best we can know it, is given by the solar system abundances of elements and isotopes (Tables 4.1 and 4.2). From this bulk material, the planets, asteroids, and comets formed, each with its own unique composition. The processes that produced these compositions separated, or fractionated, elements and isotopes from one another. By studying these elemental and isotopic fractionations, we can potentially identify the processes that separated the elements and can leam about the physical conditions involved. This is particularly important for understanding the early solar system, because its processes and conditions are not directly observable. 

Component Composition, separator gas, mole fraction Composition, stock-tank gas, mole fraction Composition, stock-tank liquid, mole fraction... 

Component Composition, separator gas, mole fraction lb mole j SP gas 1b mole j SP gas Composition, stock-tank gas, mole fraction lb mole j ST gas lb mole j ST gas Composition, stock-tank oil mole fraction lb mole j STO lb mole j res gas Composition, recombined gas, mole fraction lb mole j res gas... 

Component Composition, separator teed ZJ K-factor at 114.7 psia 75 F Kj Composition, separator liquid z,/(1+nfl(Kj-1)) i Composition, separator gas Kjxj Yi... 

Component Composition, separator, mole fraction 150 psig 120°F Composition, stock-tank, mole fraction 0 psig 80°F ... 

Potassium Aquobromruthenate, KaRu(OH2)Br5, may be prepared 3 by boiling potassium bromruthenite with alcohol and hydrobromic acid. On standing, minute brown crystals, having the above composition, separate out. 

Phase. A material of homogeneous composition separated from other phases by surfaces in a heterogeneous system, a solid, liquid, or gaseous substance which remains separated from the other phases. Different crystals... 

Dally composites were made of the 3200 kcal menu items (muffins were composited separately), homogenized and freeze-dried for analysis. Stools were freeze-dried and throughly mixed before sampling for analysis. A 50 ml aliquot of urine was dried in a porcelain crucible and dry ashed. Zinc analysis was by flame... 

DISCESSUS — Discession, or Separation, is performed when the essential potencies of a substance are separated and disjoined by the action of solvent heat. This is done by exhalation and resolution of composites. Separation by the first process occurs when a component part is so attenuated that it passes into a spirit. And that is chiefly termed exhalation when a substance is liberated and set free into the air. When it is intercepted, the process is called Distillation, or Sublimination which operations serve sometimes in place of exhalation. There is exspiration, i.e., exhalation, from things moist and from things which steam. 

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